Search

A method based on Bayer filtering to obtain color images was introduced,then the Modulation Transfer Function(MTF) of a color area Charge Coupled Device(CCD) which uses the Bayer filtering to obtain color images was established based on the discrete sampling characteristic of CCD.The MTF values for the color area CCD using Bayer filtering were compared with those of a monochrome area CCD.Obtained results indicate that the MTF value for color area CCD using Bayer filtering is notably lower than that for the monochrome area CCD.When the side length of a pixel is equal to the corresponding center distance,the MTF value at Nyquist frequency is 0.067 6 for the color area CCD using Bayer filtering while that is 0.405 3 for the monochrome area CCD.Moreover,in an imaging experiment using a resolution card,the resolution of the former is lower about 40% than that of the latter in the same imaging condition.These results are coincident with comparative analysis results of MTFs in general.

The identification and design of the roll axis servo system with a small journey range in an airborne three-axis gyro body-stabilized platform were discussed and researched by time domain and frequency domain methods.The identification method based on the genetic algorithm was presented by the time domain method and the genetic algorithm was also discussed.Moreover,the opened-loop frequency characteristics of the system were obtained according to the closed-loop frequency characteristic measuring data by the frequency domain method.These methods resolve the difficulty of roll axis servo systems with small journey range in directly measuring opened-loop frequency characteristics.On the basis of the transfer function identified,the control system corrected can meet expected indicators.Experimental results prove that the identification can nicely describe characteristics of the proposed system even in big noises,shorter journey ranges and poor measuring conditions.The closed-loop bandwidth of control system is 121 rad/s and the stability margin is 60° after correcting,which can meet the indicators of an engineer.

The (2+1)-dimensional generalized Nizhnik-Novikov-Veselov equations (GNNVEs) are investigated in order to search the influence of initial solution to exact solutions. The GNNVEs are converted into the combined equations of differently two bilinear forms by means of the homogeneous balance of undetermined coefficients method. Accordingly, the two class of exact N-soliton solutions and three wave solutions are obtained respectively by using the Hirota direct method combined with the simplified version of Hereman and the three wave method. The proposed method is also a standard and computable method, which can be generalized to deal with some nonlinear partial differential equations (NLPDEs).

In the modern military affairs, especially in the complex field, the acquirement of real-time battlefield information and intelligence is getting more and more important, most of this work is completed by aerial reconnaissance or aerial mapping equipment. Aerial mapping camera, with time-sensitive and flexible features, is playing an increasingly important role in modern warfare. With the development of technology, aerial mapping camera has also gone through several generations, gradually from film-based type to transmission type. The theory and composition of domestic and international typical aerial mapping camera is introduced from the development situation and trend in this paper. Finally, with the domestic research status, the development trend of aerial mapping camera is proposed.